Teenagers with televisions in their bedrooms eat more fast food, consume more sweetened drinks, read or study less and are less engaged with their families than those who don't have a TV where they sleep.

That's the findings of a study by University of Minnesota researchers in a report in this month's American Academy of Pediatrics journal, and follows studies on other groups of children that have found similar results.

The findings aren't that surprising, acknowledged adolescent researcher Daheia Barr-Anderson. Nor is the high number of teens who had TVs in their bedrooms. About two-thirds of the 781 teens studied from socioeconomically and ethnically diverse households in the Minneapolis-St. Paul area had TVs where they sleep. These teens on average watched four to five hours more television each week than those who didn't have TVs in their bedrooms.

A national Kaiser Family Foundation study in 2005 of children aged 8 to 18 found that 68 percent had TVs in their bedrooms.

"I think parents see it as harmless, that it's not really a big deal," Dr. Barr-Anderson said. "They know their children are safe in the home. They think they know what their children are watching."

In her study, girls with a TV in their rooms spent less time in vigorous activity each week than girls without TVs (1.8 vs. 2.5 hours). They also ate fewer fresh vegetables and had fewer family meals together. Boys with TVs not only ate less fruit and fewer family meals, they also had a lower grade-point average compared with their counterparts without TVs in their rooms.

With all the negative impact of bedroom TVs shown in these studies, why do children continue to have them in their bedrooms?

Dr. Barr-Anderson had several theories:

1) Parents upgrade the living room (or other common area TV) and are left with an "extra" TV, so it is passed along to an empty room, their child's bedroom.

2) Parents and children have different TV viewing interests and want to watch different shows. If the children have their own TV, there is less conflict on what to watch, she said.

3) Parents simply succumb to their children's urging to have their own TV (their friends may have a bedroom TV and they want one, too), she said. Besides, TVs are relatively cheap. You can get a 19- or 20-inch TV around $100.

"We're in this technologically advanced society. Everyone has TVs or video games. It is convenient for the family for children to have their own TV in the bedroom," she said. Parents "are not really realizing the extent and potential damage they're doing to the family using technology to this large extent."

So far she knows of no project or movement under way to get TVs out of children's bedrooms, but plans further study on what exactly children are watching in their bedrooms, vs. using the screentime for video games.